1. Field of the Invention
The present invention relates to an organic antireflective film composition which prevents the reflection at an underlying layer in a lithographic process, prevents stationary waves, and has a fast dry etching rate, and more particularly, the present invention relates to an organic antireflective film composition which can be used in the production of an organic antireflective film useful for semiconductor ultrafine patterning.
2. Description of the Related Art
Along with recent high integration of semiconductor elements, there is a demand for ultrafine patterns having a line width of 0.10 micrometers or less for the production of ultra-large scale integrated circuits (LSI) and the like. Accordingly, the wavelength of the light used in the exposure process has also been further shortened as compared to the region of g-line or i-line that has been conventionally used, and more attention is being paid to studies on lithography using far-infrared radiation, KrF excimer laser light, and ArF excimer laser light.
Since the size of the patterns of semiconductor elements is becoming smaller and smaller, a uniform pattern can be obtained only if the reflection ratio is maintained to be less than 1% at maximum while an exposure process is underway, and thereby an adequate process margin can be obtained, so that a desired yield can be achieved.
Therefore, in order to reduce the reflection ratio as far as possible, more emphasis is given to a technology of disposing an organic antireflective film containing organic molecules which are capable of absorbing light, below a photoresist, and thereby regulating the reflection ratio, while preventing reflection at an underlying layer and eliminating stationary waves.
Thus, the organic antireflective film composition should be able to satisfy the following requirements.
Firstly, in order to prevent reflection at an underlying layer, the composition should contain a substance which is capable of absorbing the light in the wavelength region of the exposure light source.
Secondly, during a process of laminating a photoresist after an antireflective film is laminated, the antireflective film should not be dissolved and destroyed by the solvent of the photoresist. To this end, the antireflective film should be designed to have a structure which can be cured by heat, and in a process of laminating the antireflective film, a post-coating baking process is carried out so as to achieve curing.
Thirdly, the antireflective film should be etchable faster than the photoresist in the upper part, so as to reduce the loss of the photoresist for the etching of an underlying layer.
Fourthly, the antireflective film composition should not be reactive to the photoresist in the upper part. Furthermore, compounds such as an amine and an acid should not migrate to the photoresist layer. This is because the shape of the photoresist pattern, particularly footing or undercut can be caused.
Fifthly, the antireflective film composition should have optical properties that are suitable for various exposure processes involving various substrates, that is, an appropriate refractive index and an appropriate extinction coefficient, and should have good adhesive force against substrates and photoresists.
However, under current circumstances, an antireflective film that will be satisfactory in an ultrafine pattern forming process using ArF light has not been developed.
Therefore, development of an organic antireflective substance which has high absorption against specific wavelengths, particularly in order to prevent stationary waves that occur at the time of exposure to light having a wavelength of 193 nm and reflection, and to eliminate the back surface diffraction from an underlying layer and the influence of reflected light, is currently emerging as an urgent issue.